30CrMnSiNi2A钢热处理过程的数值模拟及实验研究

发布时间：2018-03-30 17:18

  本文选题：30CrMnSiNi2A　切入点：DEFORM-HT　出处：《吉林大学》2017年硕士论文

【摘要】：30CrMnSiNi2A钢在我国工业生产的很多领域都有大量应用,除了强度性能非常突出之外其综合性能也很优异。30CrMnSiNi2A钢属于低合金超高强度钢,它是在改进中碳调质钢30CrMnSiA的过程中发展而来,合金元素的加入使得30CrMnSiNi2A钢的淬透性能良好,即使在油淬时其淬透性截面直径也超过了50mm。30CrMnSiNi2A钢在航空工业中用途广泛,可用于生产飞机起落架、机翼、航空发动机壳体以及高扭短轴类受力零部件等。为了提高该钢的强硬度、塑韧性以及抗疲劳等力学性能就需要对其进行热处理。采用传统方式探究适合材料的热处理工艺参数往往需要进行大量的试验,工作强度很大。此外由于检测设备的限制,传统的热处理工艺很难准确掌握热处理过程中材料内部相的变化情况而计算机技术的快速发展以及相变理论的逐步完善为热处理过程数值模拟技术的出现奠定了基础,它也为热处理技术走向精确化、可预测的道路提供了帮助。在热处理过程中温度以及冷却速度对材料的性能起着决定性作用。为了探究适合于30CrMnSiNi2A钢的热处理温度,本文利用DEFORM-HT软件模拟了30CrMnSiNi2A钢拉伸试样在890℃淬火后分别在200℃、250℃以及300℃下回火的热处理过程。对模拟结果进行分析后发现,当回火温度为200℃时,试样内部的马氏体基本不发生变化,试样整体的强硬度较高而塑韧性较低;当回火温度升高至250℃时,试样内部马氏体分解明显,回火马氏体含量增加。回火温度升高到300℃后试样的强硬度有了明显下降而塑韧性得到了很大地改善,它的综合力学性能更加优异。为了检验模拟结果的准确性,在实验中对30CrMnSiNi2A钢拉伸试样进行了890℃淬火,随后在200℃、250℃和300℃下进行了回火处理。利用电子拉伸试验机以及金相显微镜等仪器对试样的力学性能和不同状态下的金相组织进行了测试和观察。此外为了研究不同回火温度下拉伸试样的断裂形式和断裂机理,本文还利用扫描电镜观察了三种试样的断口微观形貌。结果表明,淬火后30CrMnSiNi2A钢拉伸试样内部生成了大量的板条马氏体,硬度显著升高。试样回火后产生了回火马氏体并且在200℃,250℃和300℃下的回火马氏体形态变化不大而硬度逐渐降低,这与回火过程中碳化物的析出以及内应力的释放密切相关。利用扫描电镜观察到经过200℃及250℃回火的试样断口分别出现了“冰糖状花样”以及“河流花样”,由此可以判断这两种试样的断裂方式属于脆性断裂,而经过300℃回火后的试样断口则出现了大量韧窝,这种断裂方式属于韧性断裂。因此对于30CrMnSiNi2A钢适宜采用淬火加低温回火的热处理工艺(例如300℃),这样可以保证它在保持高强度的同时具有一定的塑韧性,进而获得较好的综合力学性能。
[Abstract]:30CrMnSiNi2A steel has a large number of applications in many fields of industrial production in China. In addition to its outstanding strength properties, its comprehensive properties are also excellent. 30CrMnSiNi2A steel belongs to low-alloy ultra-high strength steel. It is developed in the process of improving the medium carbon quenched and tempered steel 30CrMnSiA.The addition of alloy elements makes the hardenability of 30CrMnSiNi2A steel good, and even when quenched in oil, its hardenability cross-section diameter exceeds that of 50mm.30CrMnSiNi2A steel, which is widely used in aviation industry and can be used to produce aircraft landing gear and wing.Aero-engine housing and high-torsion short-shaft bearing parts and so on.In order to improve the toughness, toughness and fatigue resistance of the steel, heat treatment is needed.It is necessary to carry out a lot of experiments and work intension to explore the heat treatment process parameters of suitable materials in traditional way.In addition, due to the limitations of testing equipment,The traditional heat treatment process is very difficult to accurately grasp the change of internal phase in the heat treatment process. The rapid development of computer technology and the gradual improvement of phase transition theory have laid the foundation for the appearance of numerical simulation technology in heat treatment process.It also helps heat treatment technology to move to a precise, predictable path.Temperature and cooling rate play a decisive role in the heat treatment process.In order to investigate the suitable heat treatment temperature for 30CrMnSiNi2A steel, the heat treatment process of tensile specimens of 30CrMnSiNi2A steel after quenching at 890 鈩，

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